lowenstein



; F. LOWENSTEIN.

METHOD OF AND APPARATUS FOR GENERATING ELECTRICAL OSCILLATIONS.

APPLICATION FILED NOV- 29,1918.

1,322,315. Patentd Nov. 18, 1919.

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F. LOWENSTEINL METHOD OF AND APPARATUS FOR GENERATING ELECTRICAL OSCILLATIONS.

APPLICATION FILED NOV- 29.1918.

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awuwto'z FRITZ LOWENSTEIN, OF NEW YORK, N. Y.

METHOD OF AND APPARATUS FOR GENERATING ELECTRICAL OSCILLATIONS.

Specification of Letters Patent.

Patented Nov. 18, 1919.

Application filed November 29, 1918. Serial No. 264,644.

To alt whom. it may concern Be it known that I, Fnrrz L()\\'ENS-1E1N, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Methods of and Apparatus for Generating Electrical Oscillations; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to methods of and apparatus for generating electrical oscillations; and it relates particularly to improvements in the so-called Poulsen arc type of apparatus for producing high frequency or radio oscillations and methods of operating the same.

As is well known, the Poulsen arc apparatus, in a typical form, comprises a. source that supplies direct current to a negative carbon electrode and to a water-cooled cylinder of copper constituting the positive electrode. The are between these electrodes is inclosed in a chamber containing an atmosphere of coal gas, hydrogen, alcohol, vapor, or the like. To increase the power and frequency of the oscillations, the arc is blown or blowed out laterally in some suitable manner, usually by means of a powerful magnetic field acting transversely to the arc.

The are is ordinarily comparatively unsteady, and when blown or bowed laterally to gain high power the irregularities are increased, causing the arc bow to swing to one or the other side of a plane intermediate the opposed pole pieces of the electromagnet device employed. When the pole pieces are too close together portions thereof are touched from time to time by the arc bow and melted away, and other parts of the apparatus may also be damaged because of the unsteadiness of the are, which unsteadiness also detrimentally affects the general operating erformance of the apparatus.

To avoid damage to the pole faces, they may of course be placed at such distance away from the mid position of the are that they will not be engaged thereby even when it swings considerably; but this increased air gap between the cores greatly increases the reluctance of the magnetic circuit. To compensate for the weakened field it therefore becomes necessary to increase the ampere-turns of the heavy magnet windings of copper, but this adds considerably to the cost of the apparatus and increases the difficulty of cooling.

It is, therefore, a principal object of my invention to provide a Poulsen arc generatmg apparatus in which the bowed arc is stabilized and maintained approximately in the desired position intermediate the opposed faces of the magnet poles, so that these faces may be brought comparatively close together, thereby reducing the air gap and the reluctance of the magnetic circuit to an extent unattainable in the type of gap apparatus heretofore known. As a consequence, ma et windings of a very much smaller num r of ampere-turns suiiice to supply the field necessary to blow the arc.

Another object of-the invention is to provide a simple, effective and inexpensive means whereby the are may be stabilized and maintained in a position where it will operate to best advantage and will not damage the pole faces or other parts of the apparatus.

Another object of the invention is to provide stabilizing means for the are that may readily be applied to Poulsen are generating apparatus now in general use, so that no substantial alterations in existing apparatus of that type will be necessary.

In carrying my invention into practice I employ means whereby an electrical force is applied in such manner as to tend to keep the blown are away from the opposed ends of the pole pieces of the blowing magnet. Such electrical force may of course be set up and applied in various ways. An ar-. rangement which I have found in practice to be especially simple and efiective consists in placing copper rings on opposite sides of the are parallel to the desired intermediate plane positions of the arc and in a position where they will be affected by changes in the magnetic field between the magnet pole pieces. The parallel copper rings are preferably mounted on the adjacent or opposing faces of said pole pieces, being most conveniently secured in annular recesses in the faces thereof. The operation of the arc causes changes in the magnetic flux, thereby inducing eddy currents in the rings, and these currents exert forces which operate to steady the blown arc and keep it away from the faces of the poles.

The foregoing and other objects and the tion here illustrated, the arc is blown or bowed by means of a magnetic field, which in this instance is set up through the agency of an electromagnet.

Referring to the drawings, 10 is the positive electrode, which is usually of copper and which may be internally water cooled in any appropriate manner; and 11 is the negative electrode usually of carbon. At 12 is one end or pole of a bar electromagnet; while above and spaced awayfro-m this pole piece is another pole piece 13 which is circular and which serves mainly to concentrate the field lines in the intervening space. Both the pole pieces are of iron, and the upper one may have radial flanges or fins 13 1 which serve not only in directing the course of the lines of force, but also as heat- .dissipating means. The electromagnet comrises energizing copper windings 14: on a laminatediron core 15, which latter may be secured to the pole piece 12 in any suitable manner, in this instance by a dove-tail connection 16. In the particular construction here shown, the arc electrodes are in axial alinement and are disposed eccentrically with respect to the circular faces of the pole pieces; This particular arrangement, while most desirable in practice, is not essential to the broad invention. The arc formed between the electrodes is inclosed in a chamher, the upper and lower walls of which are formed by the pole faces; while the lateral walls are formed by a casing or shell 17 of bronze or other nonmagnetic metal, most desirably provided with heat-dissipating fins 172, the pole pieces being most conveniently arranged to screw into this shell from above and below, as shown. In the construction illustrated, the upper pole piece is screwed down until the shoulder 131 engages the upper edge of the casing; while the position of the lower pole piece with respect to the arc can be adjusted as desired. Suitable means (not'shown) are provided for introducing hydrogen, alcohol vapor, or the like, into the arc chamber.

Under the influence of the field provided by the electromagnet, the arc is blown out laterally between the pole faces as indicated in dotted lines in Fig. 2. Means are provided for steadying the arc and preventing its being diverted to one or the other of the le faces. In the specific construction illustrated, which is a particularly desirable embodiment of the invention, such means comprise continuous or short-circuited rings 18 and 19, of copper or other highly conable manner. As here shown, each is sezUted in an annular peripheral recess formed on the pole face and is held in place by screws 20.

Any suitable method of holding the arc electrodes in position may be adopted but the present arrangement offers practical advantages. As here shown, the copper electrode is supported for longitudinal adj ustment in an internally threaded conductive bushin 21, which is mounted in a heavy insulating support 22, of porcelain or the like, secured to a hollow boss 171 on the casing by coupling member 23. A flange 24 screws into place on the end of the bushing 21, and locks the bushing firmly to the porcelain insulator. A binding post 25 carried by the locking flange, provides means. for connecting the copper electrode to the positive side of a direct current generator or other suitable source of current, the circuit being completed through the negative electrode 11 to ground by way of the metallic parts in contact therewith.

The position of electrode 10 is capable of longitudinal adjustment by virtue of its screw-thread mountin in the bushing 21; but the electrode is locked against accidental turning by the nut 26, which is normally screwe firmly against flange member 24. By backing the nut away slightly, the electrode can be readily turned in one direction or the other with the aid of a tool inserted in the kerf 261, until the desired adjustment is effected, whereupon tighteni 26 again will secure the electr e in its adjusted'position. Said nut may also aid in dissipating heat from the electrode, and to this end may be provided with fins 262.

The carbon electrode 11 is frictionally held in a metal sleeve 27, and may be fed longitudinally therein toward the other electrode by means of an abutting feed screw 28, which has a threaded connection at 29 to the sleeve 27. The sleeve 27 is longitudinall slidable in a metal tubular support 30, which screws into a hollow boss 173 on the casing or shell 17. A stop shoulder 31 on the sleeve up the nut Bil 27 is normally pressed against the inner end-12c contact with the copper electrode to close the arc circuit. Upon release of the knob 281,

the sprin operates to separate the elec-- trodes and draw the arc.

In the particular construction here illustrated, the upper pole piece 13 is hollowed out at 132 and provided with a lass window 133 through which the condition of the arc may be observed. Another window 174 may be provided in the casing 17 for the same purpose. It is to be understood that these features, while desirable in many instances are not essential to the broad invention.

The operation of the arc is apparent from the foregoing description. The'arc having been formed and blown or bowed laterally, it acts to modify the transverse blowing field created by the electromagnet, and to cause the lines of force to cut the highly conductive rings 18 and 19, therebysetting up eddy currents in said rings.

ing to repel the blown arc from both pole faces and-to maintain the same relatively steady in a position intermediate said pole faces and spaced away from both. As a result the arc is relatively steady and the destructive action on the pole faces, usual in constructions heretofore known, is practically eliminated, and the general operation of the arc is improved. As a consequence of the greater stability of the arc, it becomes possible to materially cut down the distance between said pole faces, thus diminishing the magnetic reluctance, and consequently reducing the number of ampere-turns necessary to energize the electromagnet. As the copper windings constitutethe largest factor of cost in the manufacture of the arc apparatus, a saving in this direction means a substantial reduction in manufacturing cost. Furthermore, the size of the arc chamher is reduced considerably, with the result that the explosion which always accompanies an initial starting of the arc, due to the presence of a combustible mixture in the arc chamber, is materially lessened.

\ What I claim is:

1. In electrical oscillation generating apparatus, the combination with means for producing an arc, of means for producing a bow in the arc, and means for maintaining the plane of such bowed arc substantially constant.

2. In electrical oscillation generating apparatus, the combination with means including electrodes for producing an arc, of means arranged to bow the arc, and electrical means for steadying the bowed arc.

3. In electrical oscillation generating apparatus, the combination with means for producing an arc, of electromagnetic means arranged to blow the arc, said electromagnetlc means comprising a magnetlzable These eddy currents, in turn, exert electrical forces tendpole piece and means tending to repel said are from said pole piece.

4. In electrical oscillation generating apparatus, the combination with means, including electrodes for producing an arc, of electromagnetic means arranged to blow the arc, and a highly conductive member arranged adjacent said electrodes and adapted to have eddy currents set up in it by the action of said arc. I

5. In electrical oscillation generating apparatus, the combination with means, including coaxial electrodes, for producing an arc, of electromagnetic means arranged to blow the arc, and highly conductive menibers arranged on opposite sides of said electrodes and adjacent thereto, said members being adapted to have eddy currents set up in them by the action of the arc. I

6. In electrical oscillation generating apparatus, the combination with means for producing an arc, of an electromagnet arranged to blow said arc, and means whereby the effect produced on the field by the current in said blown arc is utilized to stabilize the same.

7. In electrical oscillation generating apparatus, the combination with means, including electrodes, for producing an arc, of electromagnetic means arranged to blow the arc, said electromagnetic means com rising a magnetizable pole piece, and a shortcircuited ring associated with said pole piece and adapted to have eddy currents set up in it by the action of the blown arc.

8. In electrical oscillation generating apparatus, the combination with means, including electrodes, for producing an arc, of electromagnetic means arranged to blow the arc, said electromagnetic means comprising a pair of pole pieces between which said electrodes are disposed, and means whereby the blown arc is repelled from both said pole pieces.

9. In electrical oscillation generating apparatus, the combination with means, including electrodes, for producing an arc, of electromagnetic means arranged to blow the arc, said electromagnetic means comprising a pair of pole pieces between which said electrodes are disposed, and means whereby electrical forces are set up which act transversely of the plane of the blown arc and tend to maintain the are away from both said pole pieces.

10. In electrical oscillation generating apparatus, the combination with means, including electrodes, for producing an arc, of electromagnetic means arranged to blow the arc, said electromagnetic means comprising a pair of pole pieces between which said electrodes are disposed, and members associated with said pole nieces in such manner that the arc also-produces currents in said members acting transversely of the plane of the blown arc and tending to maintain the are away from both said pole pieces.

'11. In electrical oscillation generating apparatus, the combination with means, including electrodes, for producing an arc, of electromagnetic means arranged to blow the arc, said electromagnetic means comprising a pair of pole pieces between which said electrodes are disposed, parallel shortcircuited rings mounted on the ends of said pole pieces adjacent the arc, whereby the action of the blown arc generates currents in said rings acting transversely of the arc and tending to stabilize the same and maintain it away from the said pole pieces.

12. The method of regulating an oscillation-generating arc of the Poulsen type which comprises blowing the arc, and applying an electrical force transversely of the bloWn arc to steady the same.

13. The method of regulating an oscillaoscillations.

14. The method of generating electrical oscillations which comprises maintaining an arc in a magnetic field arranged to blow the are, and utilizing the action of the current in said are on the field to steady the are.

15. The method of generating electrical oscillations which comprises maintaining an arc in a magnetic field arranged to blow the are, and utilizing the action of the current in said are on the field to create eddy currents in planes on opposite sides of said are and adjacent thereto, said eddy currents acting to steady said arc. In testimonywhereof I signature.

FRITZ LOWEN STEIN.

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